Re: [Haskell-cafe] Re: Can we come out of a monad?

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 7/30/10 11:48 , Ivan Lazar Miljenovic wrote:

Ertugrul Soeylemez writes:

...

it's a bit hidden in Haskell, but a monad instance consists of three functions:

fmap :: (a -> b) -> (m a -> m b)

You don't even need fmap defined for it to be a monad, since fmap f m = liftM f m = m >>= (return . f)

fmap/join and return/bind are isomorphic; given either set, you can produce the other. The usual category-theory definition of monads uses the former; Haskell uses the latter, because it allows operations to easily be chained together. - -- brandon s. allbery [linux,solaris,freebsd,perl] allbery@kf8nh.com system administrator [openafs,heimdal,too many hats] allbery@ece.cmu.edu electrical and computer engineering, carnegie mellon university KF8NH -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.10 (Darwin) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAkxS9foACgkQIn7hlCsL25Uc2ACgoLG8uti3d0oWrv1H56fRJ3W4 xZIAn1KotatZklktHpKEwdib6AKXrNOr =Io9w -----END PGP SIGNATURE-----